gh-97681: Remove Tools/demo/ directory (#97682)

Remove the Tools/demo/ directory which contained old demo scripts. A
copy can be found in the old-demos project:
https://github.com/gvanrossum/old-demos

Remove the following old demo scripts:

* beer.py
* eiffel.py
* hanoi.py
* life.py
* markov.py
* mcast.py
* queens.py
* redemo.py
* rpython.py
* rpythond.py
* sortvisu.py
* spreadsheet.py
* vector.py

Changes:

* Remove a reference to the redemo.py script in the regex howto
  documentation.
* Remove a reference to the removed Tools/demo/ directory in the
  curses documentation.
* Update PC/layout/ to remove the reference to Tools/demo/ directory.